Communications systems with analog communications across an isolation barrier are sensitive to the mismatch of components used to implement the system: the component tolerances do not allow for a predictable transfer function from the transmitter circuits to the receiver circuits. There are also parasitic elements (capacitive and inductive) present in the system which may affect the predictability of the transfer function between transmitters and receivers. Further variance in the transfer function may be introduced by changing environmental conditions to which the communication system is exposed, for example, changes in temperature.
Additionally, there is continued effort to increase the bit rate of communications systems. As the bit rate increases, the sensitivity to the unpredictable gain increases, thereby increasing the possibility of errors in data transmission.